1. Field of the Invention
This invention relates to a battery charger without electrical contacts, and to the combination of this battery charger without electrical contacts and portable electronic equipment.
2. Description of Related Art
A battery charger without electrical contacts is cited, for example, in Japanese Patent Application Disclosure 2005-6440. In this type of battery charger, a battery pack contained in portable electronic equipment can be charged by placing the portable electronic equipment on top of the battery charger without connecting any electrical connectors or contacts. Consequently, the battery charger has the characteristic that batteries inside portable electronic equipment of various different forms can be charged by setting the electronic equipment on a single battery charger with no electrical contacts. For example, this characteristic allows use of many different forms of portable electronic equipment, and is particularly convenient for charging portable telephones, which rapidly change model styles.
The battery charger without electrical contacts cited in the Japanese Patent Application Disclosure 2005-6440 is provided with a pocket for inserting portable electronic equipment on a charging pad having a primary coil as shown in FIG. 5 of that disclosure. A secondary coil is housed in the portable electronic equipment. The secondary coil of the portable electronic equipment inserted in the pocket magnetically couples to the primary coil. Consequently, if high frequency electrical power is supplied to the primary coil, high frequency electrical power is induced in the secondary coil. The portable electronic equipment converts the alternating current (AC) induced in the secondary coil to direct current (DC) to charge batteries housed in the electronic equipment.
In the battery charger without electrical contacts of Japanese Patent Application Disclosure 2005-6440, the charging pad is connected to a high frequency power supply via wire leads and high frequency electrical power is supplied to the primary coil. Specifically, high frequency electrical power is input from wire leads to charge batteries in the portable electronic equipment placed in the pocket of the charging pad. Portable electronic equipment batteries cannot be charged unless the wire leads of this battery charger are connected to a high frequency power supply. In practical application, there are time constraints on portable electronic equipment such as the portable telephone, and there can be times when it is necessary to disconnect and take a telephone away from the battery charger in a state of incomplete charge. For this type of usage, the battery charger without electrical contacts of Japanese Patent Application Disclosure 2005-6440 can become unable to charge the batteries of the portable electronic equipment.
The present invention was developed to resolve this drawback. Thus, it is a primary object of the present invention to provide a battery charger without electrical contacts that can charge portable electronic equipment batteries even when input power has been cut-off.